1. Field of the Invention
The present invention relates generally to an apparatus for remotely adjusting the volume in the inflatable portion of a surgically implanted gastric band encircling the stomach. A method for treating morbid obesity utilizing a remotely adjustable gastric banding device is also disclosed.
2. Description of the Related Art
A belt-like gastric band for encircling the stomach to control morbid obesity is disclosed by Vincent in U.S. Pat. No. 5,601,604, incorporated herein by reference. The band comprises a belt that can be passed around the stomach and locked into an encircling position in order to create a stoma opening within the stomach. An adjustable portion of the band comprises an inflatable member which permits fine adjustment of the stoma opening after the stoma is created by locking the band in place.
The gastric banding procedure may involve placement of a calibrating apparatus in the stomach to position the stoma and size the pouch created above the stoma. The gastric band is fastened in position about the stomach to prevent slippage, usually by gastro-gastric sutures.
The stoma opening may be adjusted by injecting or withdrawing a fluid into or from an inflatable member, which is preferably coextensive with a portion of the inner stomach-contacting surface of the band. The means for injecting the fluid into the inflatable member usually comprises a fill port located beneath the skin that can be accessed extracorporeally by transdermal injection. Thus, following implantation, the gastric band can be adjusted to enlarge or reduce the stoma as required.
A potential disadvantage of prior art gastric bands is the difficulty in finely adjusting the stoma created by the implanted band. For example, the fill port located beneath the skin can be difficult to locate precisely. In addition, the fill procedure requires an invasive transdermal injection to adjust the band. Hence, repeated adjustments may be painful or worrisome to the patient. Moreover, exposure to x-rays may be required to facilitate location of the port. It would therefore be desirable to provide a band having an inflatable member that can be easily, precisely, and readily adjusted remotely, without the need to undergo an invasive procedure or radiographic exposure.
To address this problem, several prior art remote control gastric banding devices have been proposed. Klaiber et al. (U.S. Pat. No. 5,938,669) discloses a radio controlled gastric band adjusted by means of an electric pump and a balancing reservoir. Forsell (U.S. Pat. No. 6,210,347) discloses a remotely controlled and powered gastric band adjusted by a motorized mechanical or hydraulic means. Each of these proposed devices operates by pumping fluid to or from the gastric band. Unfortunately, because of their energy requirements, these devices pose problems for practical use. These devices are also not suitable for use with existing gastric banding systems, such as that disclosed by Vincent.
Recent developments in implantable drug delivery devices have shown that small, reliable, and energy-efficient implantable devices are feasible. Drug delivery devices currently exist in which drugs are administered periodically or continuously to a patient having an implanted device by applying pressure from a pressurized reservoir and opening an outlet valve to allow a pressure differential to cause a flow of the drug. For example, Malamud et al. (U.S. Pat. No. 5,928,195) discloses a remotely controlled drug delivery device suitable for implantation in a body cavity. A pressurized gas chamber presses upon a drug storage chamber thereby administering a dose of the drug when a valve is remotely opened.
Similarly, Arzbaecher (U.S. Pat. No. 5,607,418) discloses an implantable drug apparatus having nested deformable chambers with the outer chamber being pressurized. The pressure from the outer pressurized chamber forces the drug from a reservoir chamber into an inner dispensing chamber. A remotely controlled valve is used to administer a dose of the drug from the dispensing chamber. Further, Haller et al. (U.S. Pat. No. 6,203,523) discloses an implantable drug infusion device having a flow regulating mechanism that permits the flow rate to be independent of reservoir pressure. Some of the tradeoffs between “passive” (pressurized reservoir-based) devices and “active” (pump-based) devices are discussed in Haller, the disclosure of which is incorporated herein by reference.